RU1784873C - Device for porous material penetrability determining - Google Patents

Abstract

Field of application: membrane technique for determining the permeability of membranes used in ultrafiltration and microfiltration equipment to separate liquid media. SUBSTANCE: device consisting of a measuring cell, a supply capacity, a liquid volume meter and a recorder is additionally equipped with a clamping unit, and the liquid volume meter is made in the form of a calibrated tube with photosensors placed in it. 1 ill.

Description

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The invention relates to the field of determining the permeability of porous materials and can be used in membrane technology for non-destructive rapid control of the permeability of membranes used in ultrafiltration and microfiltration equipment for the separation of liquid media in the medical, microbiological, chemical, electronic and other related industries.

A device for determining the permeability of porous materials is known, consisting of a chamber for accommodating a test sample, made in the form of a set of flat interchangeable frames, which, together with support and sealing elements located between two plates, are tightened with tie rods and nuts.

A device is also known comprising a camera consisting of an upper movable and a lower stationary part. On the

a lower membrane is mounted, which is pressed firmly by the upper part by means of a folding clamp.

The disadvantage of these devices is the need to produce test samples of special sizes and shapes and to manually clamp the membrane in the measuring cell, which reduces the performance of determining the permeability of porous materials.

The closest technical solution to the invention is a device for determining the permeability of porous materials, containing a cylindrical measuring cell, divided by the test material into two chambers equipped with liquid supply pipelines, a flow container, while one chamber is equipped with a pressure gauge with a temperature sensor placed inside it and connected to

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the temperature controller, another, the camera is equipped with a cylindrical capacitor connected to the meter and the recorder for changing capacitance,

The disadvantage of this device is that it does not provide high accuracy and permeability determination of porous materials. This is explained by fen that the measurement of the volume of liquid flowing through a porous material is determined by changing the position of the meniscus of the liquid in the capillary, the position of which will depend on the physicochemical properties of the working fluids used, D in particular, on its surface tension and density , which introduces a significant error in the measurement of volume. In addition, the pressure is determined by measuring the change in the capacity of a cylindrical capacitor, depending on the change in the height of the liquid column in this condenser, which will also depend on the physicochemical properties of the working fluid, in particular on its dielectric constant, which will also introduce a significant error in working pressure measurement.

This device for performing measurements also requires preliminary production of samples of the test material of a special shape and size and manual clamping of the samples in the measuring cell, which reduces the measurement performance.

The purpose of the invention is to increase the productivity and accuracy of determining the permeability of porous materials.

This goal is achieved by the fact that the device is additionally equipped with a clamping unit rigidly connected to the movable upper chamber of the measuring cell and connected by pipelines to the pressure control unit from the air source and through the pressure stabilizer and controlled valves in parallel with the flow tank and through an auxiliary chamber equipped with a photosensor, with the upper chamber of the measuring cell, the flow rate through a controlled valve and the measuring capacitance is connected to the lower chamber of the measuring cell , the auxiliary chamber and the supply tank through the controlled valves are connected to the atmosphere, the liquid volume meter is made in the form of a calibrated tube with photosensors placed on it, connected in parallel to the measuring tank, the photosensors and controlled valves are electrically connected through the control unit to the electronic computing unit and the registrar.

The drawing shows a structural diagram of the device.

The device for determining the permeability of porous materials contains a measuring cell 1, which has a movable chamber 2 with a sealing ring 3, a stationary chamber 4, between

which holds the test material 5. The movable chamber 2 is mechanically connected to the clamping unit 6, to which compressed air is supplied via hoses 7 from the control unit 8 connected

with a pneumatic network. The movable chamber 2 is connected by a conduit 9 with a flow tank 10, and also with an auxiliary chamber 11 by a pipeline 12. On the auxiliary chamber 11, a photosensor 13 is placed at its lower part, which is electrically connected to the control unit 8, and a valve 14 in communication with the atmosphere is installed in the upper part . A hose 15 connects the chamber 11 through the solenoid valve 16 and the pressure stabilizer 17 to the control unit 8. The fixed chamber 4 is connected to a measuring tank 18, which is equipped with a connected optically transparent calibrated tube 19 with

photosensors 20 and 21 are mounted on it at the top. A filling funnel 22 is installed at the top of the measuring tank 18, and at the bottom it is connected via a solenoid valve 23 to a flow tank 10, which is equipped with a measuring

level 24 tube. The supply tank 10 is connected through the valve 26 to the atmosphere, and through the valve 25 and the pressure regulator 17 to the control unit 8, which is connected through the valve 16 to the auxiliary chamber

11 by a pipe 15. An electronic computing unit 27 with an indicator 28 is connected to a control unit 8.

The device operates as follows

Before starting work, the test material 5 is placed in the measuring cell 1, which is hermetically clamped in it by the clamping unit C. The working fluid is poured into the supply container 10, level

which is controlled by a measuring tube

level 24. Then the set

constant air pressure e.g. 0.5

kgf / cm2 stabilized by a stabilizer

pressure 17.

After performing these operations, the process of determining the permeability of the test material is performed automatically by the device according to a predetermined algorithm.

The initial state of the device is that all valves (14,16,23,25 and 26) are closed. From the control unit 8, a measurement command is issued. In this case, valves 14 and 25 are opened and the working fluid from the supply tank 10 under air pressure enters through the pipeline 9 into the movable chamber 2 of the cell 1, expelling air from it through the pipeline 12 into the auxiliary chamber 11 and the open valve 14 into the atmosphere.

When the chamber 2 is filled with a working fluid and it reaches the installation level of the photosensor 13, a signal is sent to the control unit 8 from the photosensor 13, by which the valve 14 closes. In this case, the working fluid under a predetermined and stabilized pressure passes through the test material 5 and the stationary chamber 4 of the cell 1 and fills the measuring tank 18 with a calibrated tube 19. When the liquid reaches the level of the photosensor 21, a signal is transmitted from it through the control unit 8 to the electronic computing unit 27 the measurement start time, i.e. the start time of the filling of the predetermined volume with the working fluid. When the liquid reaches the level of the photosensor 20, a signal is received from it through the control unit 8 to the electronic computing unit 27 about the time of the end of the measurement, i.e. the time of the end of filling with the working fluid of a given volume. Thus, the measured time of filling a given volume in the measuring tank 18 with a working fluid passing through a fixed area of the test material at a given constant pressure by the electronic computing unit 27 according to the formula

Q

V

S-t

at P const,

where Q is the permeability of the test material;

V is the given volume;

S is the fixed area of the test material; k

T is the time of filling a given volume with a working fluid;

P is the fluid pressure on the test material.

The calculated permeability value is indicated by indicator 28.

At the end of the measurement process, the operation of purging the measuring cell follows, which consists of returning the remaining working fluid from the movable chamber 2 of the cell 1 to the supply tank 10. This closes the valve 25, and the valves 26 and 16 open, and compressed

air from the control unit 8 through the pressure stabilizer 17, valve 16, line 15, chamber 11, line 12 displaces the remaining liquid from chamber 5 2 through line 9 to the supply tank

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After purging is complete, valves 14 and 16 close and valve 23 opens. In this case, the working fluid is drained from the measuring tank 18 and the calibrated tube 19 into the flow tank 10. After the drain is finished, the valves 23 and 26 are closed and the device is ready for operation again. Measuring cell 1 at Ј; timing

5 is drained after purging, and is therefore also ready to place a new sample of the test material in it. On command from the control unit 8, the node 6 presses out the test material in cell 1 and after it

0 removal, the next one is placed in it, which is clamped tightly in the cell, also on command from the control unit 6.

An example of a specific implementation. A device for determining the permeability of porous materials is implemented as a part of a measuring cell with an automatic clamping unit of the test material in it, a measuring capacitance with photosensors, and an electronic

0 block. The movable chamber of the measuring cell is equipped with an auxiliary chamber with a volume of about 20 cm from the conditions of the total volume of the movable chamber of the measuring cell and the volume of the piping. The clamping unit is a pneumatic cylinder operating at a pressure from the pneumatic network of the order of 2.5 kgf / cm and automatically controlled by the solenoid valves of the control unit.

0 The area of the test material, fixed by the sealing ring of the movable chamber of the measuring cell through which the working fluid is passed, is 13.85-10 4 m2. Working pressure

5 liquid per test material is stabilized and has a value of 0.5 ± 0.025 kgf / cm, set using a pressure regulator-stabilizer type SRD-03, and is indicated by a voltmeter type

0 F-217.

Photo sensors installed on a calibrated glass tube and on an auxiliary camera made of 5 glass are also implemented on AL-107 photodiodes and FD-27K type LEDs operating in the infrared region of the spectrum in a valve mode, providing high noise immunity.

The volume filled with the working fluid in the measuring vessel is set and fixed by the position of the photosensors on the calibrated tube using a micrometer screw. The diameter of the calibrated tube is much smaller than the diameter of the measuring capacitance, for example, 3 and 30 mm, which ensures stability and accuracy in setting the measured volume.

The control unit of the device is equipped with SKN-2 type solenoid valves, which are turned on by thyristor switches according to the commands programmed in the electronic computing unit. The block has been made on 155 series microcircuits and has an LED indicator that provides permeability measurements in the range from 500 to 50,000 with an accuracy of no more than 1%.

The proposed device provides the following advantages in comparison with the known one: the accuracy of measuring the permeability of porous materials is significantly improved since the device excludes the dependence of measurements on the physicochemical properties of the working fluids used; eliminated the need for preliminary manufacturing of special sizes and shapes of samples of the test material for permeability measurements, as well as the ability to quickly change the test material in the measuring cell by introducing into the device an automatic clamping unit, as well as an electronic computing unit that automatically calculates the measurement results, which dramatically increased the permeability measurement of porous materials.

FORMULA AND ZOBRETIN

A device for determining the permeability of porous materials containing a measuring cell, consisting of an upper movable and lower stationary chambers, pipelines for supply and removal

a liquid, a supply container connected to the measuring cell, a liquid volume meter and a recorder, characterized in that, in order to increase productivity and accuracy of determination,

it is additionally equipped with a clamping unit rigidly connected to the movable upper chamber of the measuring cell and connected by pipelines to the pressure control unit from the pneumatic source and

through a pressure stabilizer and controlled valves in parallel with the expendable bone and through an auxiliary chamber equipped with a photosensor, with the upper chamber of the measuring cell,

the capacitance is connected through the controlled valve and the measuring capacitance to the lower chamber of the measuring cell, the auxiliary chamber and the supply capacitance are connected to the atmosphere through the controlled valves, the liquid volume meter is made in the form of a calibrated tube with photo sensors placed on it, connected in parallel to the measuring capacitance, photosensors and controlled valves are electrically connected through the control unit to the electronic computing unit and the recorder.

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